## Book I. Propositions 9 and 10Problems Back to Propositions 9 and 10. 1. Draw an angle, and bisect it. 2. a) In Proposition 9, what are we given? To see the answer, pass your mouse over the colored area. An angle. 2. b) What are we required to do? Bisect it. 2. c) Practice Proposition 9. 3. Use Proposition 9 to prove: Let ABC be an isosceles triangle with AB equal to AC. Then angle ABC is equal to angle ACB Bisect angle BAC with the straight line AD. Then, since BA is equal to CA, and AD is common to the two triangles ADB, ADC, therefore angle ABD is equal to angle ACD. 4. Draw a straight line, and bisect it. 5. a) In Proposition 10, what are we given? A straight line. 4. b) What are we required to do? Bisect it. 5. c) Practice Proposition 10. Table of Contents | Introduction | Home Please make a donation to keep TheMathPage online. Copyright © 2012 Lawrence Spector Questions or comments? E-mail: themathpage@nyc.rr.com |